I don't know how much steam the Spider-Man franchise can keep up, but it would be kinda cool to see them build to a Sinister Six confrontation. So long as they don't do what they did with the Rami Spidermans and the Burton Batmans. I hate when studios feel that they need to make it "more exciting" by simply adding another villain. If one was exciting, two makes it more exciting, we saw him fight now, now lets have him fight three... that gets a little old fast.
Forthcoming
2013
The Wolverine
Thor: The Dark World Marvel Studios
2014
Captain America: The Winter Soldier
The Amazing Spider-Man 2 Columbia Pictures
X-Men: Days of Future Past 20th Century Fox
Guardians of the Galaxy
Announced
2015
Untitled Fantastic Four reboot
Untitled The Avengers sequel
Ant-Man
2016
Unrevealed Marvel Studios film Only release date revealed
Third The Amazing Spider-Man film
Unrevealed Marvel Studios film
2017
Unrevealed Marvel Studios film
2018
Fourth The Amazing Spider-Man film
_________
As of now that is the official lineup for all marvel films currently in development.
From what I can see for ASM is definitely a build up to the SS; what with #2 featuring Electro and Rhino and the first with Lizard.